We all know that with MoP came account-wide mounts, pets, achievements, etc. Personally, I love this, because now I can have most of my perks on any toon.
And on that note, I have an idea: why not make secondary professions shared across accounts too? One can understand why primary professions aren't account-wide: each one has a unique perk, and the combinations of those perks make the toon unique. But secondary profs have nothing like that. It's the exact same for each toon.
For example, I have my Horde toons on one server and my Alliance toons on another. On the Horde side, my Hunter can handle the cooking, but I have no max-Cooking Alliance toon; I would have to level cooking all over again. The point is, it would be much more convenient to have all that on any toon instead of just certain toons.